select user_id
from order_info
where datediff(date,"2025-10-15")>0
  and status = "completed"
  and product_name in("C++","Java","Python")
group by user_id
having count(id)>=2
order by user_id

select oi1.user_id 
from order_info oi1
left join (
    select oi2.user_id , count(user_id) cnt
    from order_info oi2
    group by oi2.user_id
) x using (user_id)
where datediff(date,"2025-10-15")>0
    and status ="completed"
    and product_name in("C++","Java","Python")
    and x.cnt >= 2
    group by oi1.user_id